<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>allUniqueBy</title>
</head>

<body>
    <div>打开浏览器控制台查看结果</div>
    <script>
        const allUniqueBy = (arr, fn) => arr.length === new Set(arr.map(fn)).size;
        console.log(allUniqueBy([1.2, 2.4, 2.9], Math.round)); // true
        console.log(allUniqueBy([1.2, 2.3, 2.4], Math.round)); // false
    </script>
</body>

</html>